Anodized aluminum material is used mainly because it is light, strong, and corrosion-resistant. While raw aluminum does offer a certain amount of durability and scratch resistance, it is prone to oxidation, dents, and scratches, which can change it in the long term and keep it looking good. To make the aluminum stronger and more durable, it is then anodized to form a protective oxide layer on its surface. The reason for this layer is that it hardens the metal, giving it a more noncorroding and nonwear surface and a more pleasant appearance. Anodized aluminum is preferred due to these factors and is used widely across aerospace, automotive, construction, and consumer electronics industries. The anodization consists of several steps cleaning of the surface, immersion into an electrolyte bath, oxidation using electric current, and sealing. Besides making the material stronger, this treatment can be colored in different shades and finishes. Electrolytic coloring, Dip coloring, Integral coloring, and Interference coloring are different common coloring techniques. Ordinary anodizing and hard anodizing are the two main types of anodizing. Typically there are two processes available: ordinary anodizing, used primarily for finish and low-weight applications, and hard anodizing which gives excellent durability, wearer, and strength for military, industrial, and aerospace applications. In addition to anodization, aluminum can be processed through other surface treatments such as electroplating, powder coating, chromate conversion coating, PVD coating, ceramic coatings, or hot dip galvanizing. Anodized aluminum does not possess these properties uniformly and thus is used as a versatile and reliable material in many industries, with each method providing the material with specific enhanced properties—corrosion resistance, hardness, conductivity, etc. In this article, we’ll discuss what properties, benefits, applications, and maintenance of anodized aluminum involve, and why it is a better alternative to other metals and treatments. If we know these aspects we can understand which material to use for a particular industry and the consumer. What is Anodized Aluminum? Aluminum that has been anodized is an aluminum that has been run through an electrochemical process to produce a thicker, more durable oxide layer on its surface. The presence of this anodic oxide layer increases the resistance of the metal to corrosion, improves the surface hardness, and increases the ability of the metal to adhere to dyes and coatings. The Anodization Process In other words, the anodization process includes several key steps. Anodized Aluminum Material Key Properties 1. Enhanced Corrosion Resistance Anodized aluminum is one of the most resistant to corrosion. This makes it practically useless outdoors or when submerged in water, as the oxide layer protects the metal from moisture and our environment. 2. Increased Surface Hardness Anodization improves the hardness of aluminum significantly and aluminum becomes more resistant to scratch, dent, and wear. One such hard anodized aluminum is highly durable and is indeed used in high-performance applications. 3. Aesthetic Appeal and Color Variety Also, anodized aluminum is offered in black, gold, bronze, silver, etc. without changing the natural texture of the metal. This is why it is a preferred choice for architectural as well as decorative applications. 4. Lightweight Yet Strong While the oxide layer is put on top of the aluminum, this doesn’t make the aluminum significantly heavier, and it is still lighter than heavier materials such as stainless steel. 5. Electrical Insulation Because anodized aluminum is a poor conductor of electricity as compared to untreated aluminum, it is an attractive material to use in applications where insulation is needed for electrical or electronic purposes. 6. Environmentally Friendly and Sustainable Anodized aluminum is completely non-toxic, is recyclable, and does not out-gas dangerous and health-harming VOCs (volatile organic compounds), so it is eco-friendly. How to Add Color to Anodized Aluminum Parts? Anodizing aluminum is well known to be able to hold colors very vibrantly. Electrolytic coloring and dip coloring are the two of the many techniques used to color anodized aluminum. 1. Electrolytic Coloring One popular way to beautify anodized aluminum is with electrolytic coloring whereby anodized aluminum is colored with durable and UV-resistant shades. Once the aluminum has gone through the anodizing process, it is placed in a bath with metallic salts. In the last few years metalized salts have been developed whereby, when an electric current is applied, they settle into the open pores of the anodized surface permanently creating a metal-colored surface. Finally, the color depends on the type of metal salts involved. Copper salts ,for instance, make the solution reddish in tone, and other metals can make it in other hues. It is widely used because colors done this way last long and don’t fade, which makes it great for outdoor or high-exposure uses. 2. Dip Coloring Another color method is ‘dip coloring’ which gives one a large variety of color choices. During this kind of processing, the porous layer is submerged in a dye solution where the anodized aluminum absorbs the pigment. Once a shade is reached, the aluminum is sealed in water to stop reactions from continuing. Dip coloring offers much more vibrant and customizable contrasted shades, but they are not UV resistant and the colors will fade to a much lesser extent when exposed to sunlight. However, this lack of durability is the main reason why it is not commonly used in applications where the durability of parts is an important factor. 3. Integral Coloring (One-Step Process) An integral coloring is a unique process that incorporates anodizing and coloring into one process which is more efficient than in multi-step methods. Unlike some other techniques, the electrolytes, which react with the surface of the aluminum and are quick to dry, create deep, rich metallic tones including black, gold, or bronze. The color is formed in the very oxide layer, and due to that, it is very durable and doesn’t scratch, isn’t prone to corrosion, and doesn’t fade away. While integral coloring yields quality finishes, it is rare because of the cost and complexity. Architectural components, high-end electronics, and industrial equipment in which the parts must be able to withstand demanding conditions where
